What is HEPA?
HEPA stands for high-efficiency particulate air. A HEPA filter is a type of mechanical air filter; it works by forcing air through a fine mesh that traps harmful particles such as pollen, pet dander, dust mites, and tobacco smoke. Selecting and Using an Air Filter. You can find HEPA filters in most air purifiers.Dec 4, 2016
HEPA Filter Benefits for Allergy Relief - WebMD
High-efficiency particulate arrestance (HEPA), originally
called high-efficiency particulate absorber but also
sometimes called high-efficiency particulate arresting or
high-efficiency particulate air, is a type of air filter. Filters
meeting the HEPA standard have many applications,
including use in medical facilities, automobiles, aircraft
and homes. The filter must satisfy certain standards of
efficiency such as those set by the United States
Department of Energy (DOE).
To qualify as HEPA by US government standards, an air
filter must remove (from the air that passes through)
99.97% of particles that have a size of 0.3 µm.
HEPA was commercialized in the 1950s, and the original term became a registered trademark and later a generic term for highly efficient filters.
HEPA original filter for Philips FC87xx-series vacuum cleaners. Many vacuum cleaners also
use HEPA filters as part of their filtration systems. This is beneficial for asthma and
allergy sufferers, because the HEPA filter traps the fine particles (such as pollen
and dust mite feces) which trigger allergy and asthma symptoms. For a
HEPA filter in a vacuum cleaner to be effective, the vacuum cleaner
must be designed so that all the air drawn into the machine is
expelled through the filter, with none of the air leaking past it.
This is often referred to as "Sealed HEPA" or sometimes the
more vague "True HEPA". Vacuum cleaners simply labeled
"HEPA" may have a HEPA filter, but not all air necessarily passes
through it. Finally, vacuum cleaner filters marketed as "HEPA-like" will
typically use a filter of a similar construction to HEPA, but without the filtering efficiency. Because of the extra density of a true HEPA filter, HEPA vacuum cleaners require more powerful motors to provide adequate cleaning power.
Some newer models claim to be better than the first models because of "washable" filters. Generally, washable true HEPA filters are expensive. Some manufacturers claim filter standards such as "HEPA 4", without explaining the meaning behind them. This refers to their Minimum Efficiency Reporting Value (MERV) rating. These ratings are used to rate the ability of an air cleaner filter to remove dust from the air as it passes through the filter. MERV is a standard used to measure the overall efficiency of a filter. The MERV scale ranges from 1 to 20, and measures a filter's ability to remove particles from 10 to 0.3 micrometre in size. Filters with higher ratings not only remove more particles from the air, they also remove smaller particles.
The original HEPA filter was designed in the 1940s and was used in the Manhattan Project to prevent the spread of airborne radioactive contaminants. It was commercialized in the 1950s, and the original term became a registered trademark and later a generic term for highly efficient filters.
Over the decades filters have evolved to satisfy the higher and higher demands for air quality in various high technology industries, such as aerospace, pharmaceutical drug processing, hospitals, health care, nuclear fuels, nuclear power, and integrated circuit fabrication.